If the old Microsoft 365 subscription is tied to a Microsoft account that can’t be accessed, there is no supported way to move that subscription to the new account. The supported path is to cancel the old subscription from the original account, then use the new subscription on the new account.
For a normal self-service cancellation, the steps are:
- Go to https://account.microsoft.com/services/microsoft365.
- Sign in with the same Microsoft account that purchased the old subscription.
- Select Manage.
- Select Cancel or Upgrade or Cancel.
- Follow the prompts to complete cancellation.
If Turn on recurring billing appears instead of Manage or Cancel, the subscription is already set to expire and no further action is required. It will continue until the shown expiry date and won’t be charged again.
If the subscription was purchased through Google Play, the Apple App Store, or another third-party retailer, cancellation must be done through that seller.
Because sign-in to the old account is not possible, the available guidance in this scenario is to contact Microsoft Support. If support still can’t access the account because of the old sign-in and verification details, a Microsoft Q&A accepted answer recommends asking the bank or card provider to stop the recurring Microsoft charges.
Also note: when a Microsoft 365 subscription is canceled or expires, included storage benefits are reduced. Back up any OneDrive files that are still needed before the old subscription ends.